The present invention relates generally to methods and apparatus for cooling patients for therapeutic purposes, and more particularly to systems for treating brain trauma and brain ischemia such as that caused by cardiac arrest by inducing hypothermia in a patient.
It has been discovered that the medical outcome for a patient suffering from severe brain trauma or from ischemia caused by stroke or heart attack is degraded if the patient""s body temperature rises above normal (38xc2x0 C.). It is further believed that the medical outcome for many such patients might be significantly improved if the patients were to be cooled relatively quickly for a short period, e.g., 12-72 hours.
Systems and methods have been disclosed that propose cooling blood flowing to the brain through the carotid artery. An example of such systems and methods is disclosed in co-pending U.S. patent application Ser. No. 09/063,984, filed Apr. 21, 1998, owned by the present assignee and incorporated herein by reference. In the referenced application, various catheters are disclosed which can be advanced into a patient""s carotid artery and through which coolant can be pumped in a closed circuit, to remove heat from the blood in the carotid artery and thereby cool the brain. The referenced devices have the advantage over other methods of cooling (e.g., wrapping patients in cold blankets) of being controllable, relatively easy to use, and of being capable of rapidly cooling and maintaining blood temperature at a desired set point.
As recognized in co-pending U.S. patent application Ser. No. 09/133,813, filed Aug. 13, 1998, owned by the present assignee and incorporated herein by reference, the above-mentioned advantages in treating brain trauma/ischemic patients by cooling can also be realized by cooling the patient""s entire body, i.e., by inducing systemic hypothermia. The advantage of systemic hypothermia is that, as recognized by the present assignee, to induce systemic hypothermia a cooling catheter or other cooling device need not be advanced into the blood supply of the brain, but rather can be easily and quickly placed into the relatively large vena cava of the central venous system. Moreover, since many patients already are intubated with central venous catheters for other dinically approved purposes anyway, providing a central venous catheter that can also cool the blood requires no additional surgical procedures for those patients. A cooling central venous catheter is disclosed in the present assignee""s co-pending U.S. patent application Ser. No. 09/253,109, filed Feb. 19, 1999 and incorporated herein by reference.
The present invention recognizes that a patient requiring hypothermia preferably be cooled down relatively rapidly. Thus, catheters with high cooling capacities, such as the catheter that is the subject of the second of the above-referenced applications, are desirable. As recognized herein, however, it is not necessary to maintain a high capacity catheter in a patient once the patient has been cooled, provided a catheter with lower cooling capacity is used to maintain temperature at the desired level. The present invention understands that such a lower cooling capacity catheter, which can be configured as, e.g., a central venous catheter to facilitate uses other than just cooling, can be advantageously used to replace the higher capacity catheter to maintain temperature.
A kit for lowering and maintaining temperature in a patient includes a groin catheter having at least one fluid circulation passageway connectable to a source of coolant. The groin catheter is configured for placement in a patient""s circulatory system through a groin entry point. A neck catheter has at least one fluid circulation passageway connectable to a source of coolant, with the neck catheter being configured for placement in a patient""s circulatory system through a neck entry point.
In a preferred embodiment, the groin catheter has a first cooling capacity and the neck catheter has a second cooling capacity less than the first cooling capacity. Both catheters preferably have respective heat exchange regions that are established by one or more balloons.
In another aspect, a method for establishing and maintaining a predetermined temperature in a patient includes lowering the patient""s temperature to a desired level using a groin catheter at least partially placed in the venous system of the patient, and maintaining the temperature at the desired level using a neck catheter having a heat exchange region.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: